Recently, silver halide color photographic materials which can be processed in a rapid processing system and which have excellent color reproducibility, color image quality and color image storage stability have been sought.
In particular, the rapid processability of the materials is important. The materials exposed are continuously processed in an automatic developing machine as installed in laboratories, and it is requested that the materials are developed within the day to deliver the finished prints to the user, as part of improvement of the services to users. In these days, it is further requested to deliver the finished prints to the user within several hours after receipt of the photographic materials to be processed, and such request is increasingly augmented.
In addition, reduction of the processing time may bring about improvement of the production efficiently and may facilitate reduction of the production cost, and therefore, development of rapid processing systems is earnestly required.
Various approaches have heretofore been made to the success of satisfactory rapid processing means from both the aspects of the photographic materials and the processing solutions. Regarding color development, various means of elevating the temperature of the processing solution, elevating the pH value of the solution or adding a color developing agent of high concentration have been tried and proposed. In addition, it is also known to add various additives such as a development accelerator to the processing solution.
As the development accelerator for this purpose, there are mentioned, for example, 1-phenyl-3-pyrazolidone described in British Patent 811,185, N-methyl-p-aminophenyl described in U.S. Pat. No. 2,417,514, and N,N,N',N'-tetramethyl-p-phenylenediamine described in JP-A-50-15554. (The term "JP-A" as referred to herein means an "unexamined published Japanese patent application".)
However, sufficient rapid processing could not be attained by the above means, which would rather cause deterioration of the photographic characteristics, for example, elevation of fog of the materials.
On the other hand, it is known that the shape, size and composition of the silver halide grains in the silver halide emulsions to be used in preparing photographic materials have a great influence on the developing speed of the photographic materials. In particular, the halogen composition has a significant influence thereon, and it is known that photographic materials containing a silver halide emulsion having a high silver chloride content have an extremely high developing speed.
Formation of color images in silver halide color photographic materials is generally effected by a system in which the silver halide grains in the exposed silver halide color photographic material are reduced by an aromatic primary amine developing agent whereupon the developing agent is thereby oxidized, and the oxidation product of the developing agent is coupled with the coupler which is previously contained in the silver halide color photographic material to form a color image. Generally, three couplers for forming the three colors of yellow, magenta and cyan, respectively, are employed as the couplers in the system, as the color reproduction is effected by a subtractive color photographic process.
In order to perform a better color reproduction, satisfaction of extremely numerous elements and conditions is necessary. Specifically, such elements and conditions include the color sensitivity and interlayer effect of picture-taking photographic materials, the matching balance between the spectral sensitivity of the printing photographic material and the color formed on the picture-taking photographic material, the overlapping of the spectral sensitivity between the light-sensitive layers each having a different color sensitivity, the spectral absorption characteristics of the colored dyes, and the color mixing (during processing) between the light-sensitive layers each having a different colored dye. All of such elements and conditions have influences on the level of the color reproducibility of photographic materials.
Recently, a new system has been developed and is being put to practical use in order to meet the above-mentioned request for rapid processing, in which the above-mentioned emulsion having a high silver chloride content is employed in preparing a photographic material and the material is processed with a processing solution not containing a sulfite and benzyl alcohol which are contained in the color developer for the conventional color paper. However, the new system has a serious drawback in the point of the above-mentioned color-mixing. That is, it has been found that the color-mixing is extremely noticeable in the process of the new system, as compared with the conventional processing system.
The fundamental properties which are essential to couplers include not only a high solubility in high boiling point organic solvents, a high dispersibility and dispersion-stability in silver halide emulsions without easy precipitation and the favorable photographic characteristics, but also a pertinent spectral absorption characteristic of the colored dye which is favorable to the color reproducibility and a sufficient fastness of the colored dye to light, heat and moisture. In particular, the spectral absorption characteristic of the colored dye is extremely important for color photographs. Even though couplers capable of forming color dyes having a favorable spectral absorption characteristic are incorporated into photographic materials, the meaning of use the coupler would remarkably lower if the above-mentioned color-mixing occurs in the processed photographic materials.
In color photographs, the color image fastness is also as important theme. Above all, the color image fastness to light is more important. In the color papers which are presently used, fading of magenta dyes and formation of brown stains to be caused by photo-reaction of the non-colored magenta couplers are significant problems to be solved. As a means of improving magenta couplers so as to overcome the problems, a technique of using 2-equivalent 5-pyrazolone couplers in place of the conventional 4-equivalent 5-pyrazolone couplers is known. Such magenta couplers include, for example, the nitrogen atom-releasing type magenta couplers described in U.S. Pat. No. 4,310,619 and the sulfur atom-releasing type magenta couplers described in U.S. Pat. No. 4,351,897. In particular, the arylthio group-releasing type magenta couplers described in the latter have many practically excellent aspects including the stability of the couplers themselves.
As magenta couplers other than 5-pyrazolone couplers, there are known pyrazoloazole magenta couplers. The couplers of this type are known to form color dyes having a better spectral absorption characteristic than 5-pyrazolone couplers and additionally having an excellent light-fastness. Further, it is also known that thsee couplers themselves do not cause stains so much. Accordingly, couplers of this type are also practically useful. They are described for example in U.S. Pat. Nos. 3,369,879 and 3,725,067, Research Disclosure, Item No. 24220 (June, 1984), ibid., Item No. 24230 (June, 1984), U.S. Pat. Nos. 4,500,630 and 4,540,654, JP-A-61-65245 (corresponding to EP 177765), JP-A-61-65246 ( corresponding to U.S. Pat. No. 4,822,730), and JP-A-61-147254 and European Patent 0,226,849. Among the pyrazoloazole magenta couplers, pyrazolo [5,1-c][1,2,4]triazoles and pyrazolo[1,5-b][1,2,4]triazoles are preferred in view of the total properties of the color forming property, the spectral absorption characteristic of the colored dyes formed therefrom and the color image fastness of the dyes. In particular, the pyrazolo[1,5-b][1,2,4]triazoles described in U.S. Pat. No. 4,540,654 are preferably employed. Further, derivatives of such couplers, for example, those formed by combining a branched alkyl group as the substituent (described in JP-A-61- 65245), those formed by introducing a sulfonamido group into the molecule (described in JP-A-61-65246 ) , those formed by introducing an alkoxysulfonamido group (described in JP-A-61-147254), and those formed by introducing an alkoxy group or an aryloxy group into the 6-position (described in European Patent 0,226,849), are more preferred.
However, when so-called 2-equivalent couplers having a releasing group other than hydrogen atom in the coupling position, which are among the couplers having various advantages as mentioned above, are used in a green-sensitive silver halide emulsion layer, it has been found that color-mixing is unfavorably noticeable in the processing mentioned above.